Endace DAG 7.1S, User Manual

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EDM 01-17 DAG 7.1S Card User Guide
Chapter 4:
Capturing Data
Starting a
Session
For a typical data capture session follow the steps listed below:
•
Move to the
dag
directory,
•
Load the appropriate driver,
•
Then load the appropriate FPGA image to each DAG card. For
example, for ATM or PoS capture with one DAG 7.1S card installed
use:
dagrom -rvp –d dag0 -f xilinx?????????????
•
Set the integrity of the card’s physical layer and check the integrity of
the physical layer to each DAG card. For example:
dagthree –d0 dag0 default
•
Start the capture session using:
tools/dagsnap -d dag0 –v -o tracefile
Note: You can use the
-v
option to provide user information during
a capture session although you may want to omit it for automated
trace runs.
By default
dagsnap
will run indefinitely but can be stopped using
CTRL+C . You can also configure
dagsnap
to run for a fixed time period
then exit.
Setting
Captured
Packet Length
Snaplength
You can use
dagconfig
to set the length of the packets you want to
capture.
By default the snaplength (
slen
) which is the portion of the packet that
you want to capture, is set to 48. This means that only the first 48 bytes of
each packet will be captured. If for example you want to capture only the
IP headers you may want to set the length to a smaller value. Alternatively
if you want to ensure you capture the whole packet you may want to set
the length to a larger value.
Note: The snaplength value must be a multiple of 4 and in the range
of 16 to 2040.
©2006 25 Version 2: May 2006